Effects of frozen storage duration and soil temperature on the stomatal conductance and net photosynthesis of Picea glauca seedlings

Nursery grown seedlings of Picea glauca (Moench) Voss were stored frozen in the dark from approximately 10-31 weeks, thawed and grown for 28 days in a growth chamber at three soil temperatures (3, 7, and 11 degrees C). During the growing period gas exchange measurements were made every three days. Seedling net photosynthesis (pn) and stomatal conductance (gs) showed significant interactions between soil temperature and storage duration treatments. Soil temperature did not affect seedling gs or pn, though the degree and extent of storage duration effects were dependent on soil temperature. Recovery of gs occurred over a 4-7 day period from low levels after planting. Seedlings stored longer than 22 weeks showed lower rates of pn than those stored for shorter durations. The lower pn in long-stored seedlings did not result from stomatal limitations to carbon fixation, as gs increased in seedlings stored 22 weeks